Mechanical pipe couplings provide various advantages over other techniques for joining pipe elements end to end. For example, they are less expensive to install than welded joints, which require skilled welders and the use of an exposed flame or arc, which are not practical or safe in every environment. Mechanical couplings may also be designed to afford a degree of flexibility at the joint, unlike welded joints which are substantially rigid. Flexibility is desired because it facilitates design and assembly of the piping network, allowing for larger dimensional and angular tolerances. Couplings which permit flexibility also impose lower stresses on pipe elements when external forces are applied to the pipes. Flexibility also allows for greater expansion and contraction under temperature changes without compromising the fluid tight integrity of the various joints. It would be advantageous to have a mechanical pipe coupling which is usable to join pipe elements having circumferential rings located at the ends of each pipe element and which provides for angular flexibility of the pipe elements without compromising the fluid tight integrity of the joint.